Surgical fasteners have been used to connect various combinations of tissue, prostheses and graft materials. For example, fasteners have been used to connect tissue and graft in vascular anastomoses in conventional or minimally invasive procedure.
Minimally invasive surgery has allowed physicians to carry out many surgical procedures with less pain and disability than conventional, open surgery. In performing minimally invasive surgery, the surgeon makes a number of small incisions through the body wall to obtain access to the tissues requiring treatment. Typically, a trocar is delivered into the body with a cannula. After the trocar pierces into the body cavity, it is removed and the cannula is left with one end in the body cavity.
When a minimally invasive procedure is done in the abdominal cavity, the retroperitoneal space, or chest, the space in which the operation is performed is more limited, and the exposure to the involved organs is more restricted, than with open surgery. Moreover, in a minimally invasive procedure, the instruments used to assist with the operation are passed into the surgical field through cannulae. When manipulating instruments through cannulae, it is extremely difficult to position tissues in their proper alignment with respect to each other, pass a needle through the tissues, form a knot with the suture material once the tissues are aligned, and prevent the suture material from becoming tangled.
The fastening of body tissues together, or of fastening body tissues to graft materials becomes much more difficult in the restricted spaces imposed upon a surgeon when working though cannulae. Because the use of sutures is often difficult if not impossible in these situations, various other forms of fasteners have been developed to simplify the joining together of tissues and tissues with grafts in these environments, as well as in more conventional surgical procedures.
PCT publication nos. WO 99/62406 and WO 99/62409, which are commonly assigned to the assignee of the present application, disclose tissue connector assemblies having a clip movable between an open state and a closed state and a mechanical restraining device attached to the clip for restraining the clip in its open state. The clip has a generally U-shaped configuration when in its open state. A needle may be releasably attached to the clip. This type of tissue connector assembly is discussed further below and in PCT publication nos. WO 99/62406 and WO 99/62409, which are incorporated herein, by reference thereto, in their entireties.
In some cases, as with sutures, however, the surgeon may find that the placement of a particular fastener is undesirable. Fasteners so deployed have been removed by simply cutting, as done with sutures. However, this may be difficult depending on the size and material of the fastener. Cutting may be especially difficult when the fastener is metal. In addition, cutting may cause a portion of the fastener to break down into small fragments which can then enter the bloodstream. Therefore, there is a need for a surgical fastener removal system that can easily and reliably remove a fastener after it has been deployed.